logging: deploy logviewer v0.1.0 behind oauth2-proxy (#404)

## Why

The logviewer UI gives browser access to the ClickHouse log store (`logreader` user). It must only be reachable by authorized users, so it sits behind an Authentik-gated oauth2-proxy front at https://logviewer.unkin.net, mirroring the arrstack front-door and mediamover/pdbmux gateway patterns.

## Changes

- Adds the logviewer Deployment (1 replica, `docker-internal/logviewer:v0.1.0`) reading ClickHouse at `clickhouse-logs` via the existing `clickhouse-logreader` Secret, `/healthz` probes, nonroot securityContext
- Adds an oauth2-proxy (quay.io/oauth2-proxy/oauth2-proxy:v7.15.3) front with issuer `https://identity.unkin.net/application/o/logviewer/`, `ak_groups` claim, allowed group `akP-logviewer-admin`, internal-CA trust via the combine-certs initContainer
- Syncs kv `kubernetes/namespace/logging/default/oauth-credentials` into the `logviewer-oauth-credentials` Secret via the existing `default` VaultAuth (kv path already seeded; no terraform-vault change needed)
- Adds ClusterIP Services for the app and the oauth2-proxy front door
- Adds internal Gateway + HTTPRoutes for `logviewer.unkin.net` (vault-issuer cert, external-dns -> 198.18.200.4, http->https redirect)
- Registers `logviewer/` in the logging base kustomization

## Dependency

Login requires the Authentik `logviewer` provider/application from terraform-authentik PR #21. This PR is safe to merge first: the VSO secret sync and the deployment come up regardless; OIDC login only works once #21 is applied.

Validated with `kustomize build` (base + au-syd1 overlay) and kubeconform (49/49 valid).

Reviewed-on: #404
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

apps/base/logging/kustomization.yaml

@@ -15,6 +15,7 @@ resources:
   - serviceaccount_logarchiver.yaml
   - configmap_logarchiver.yaml
   - deployment_logarchiver.yaml
+  - logviewer
 
 # Vector pipelines are the single source of truth (also validated by
 # `vector test` in CI). Mounted into each tier via `existingConfigMaps`.

apps/base/logging/logviewer/deployment.yaml

@@ -0,0 +1,80 @@
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: logviewer
+  namespace: logging
+  annotations:
+    secret.reloader.stakater.com/reload: "clickhouse-logreader"
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: logviewer
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        app: logviewer
+    spec:
+      serviceAccountName: default
+      automountServiceAccountToken: false
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 65532
+        runAsGroup: 65532
+        fsGroup: 65532
+        seccompProfile:
+          type: RuntimeDefault
+      containers:
+        - name: logviewer
+          image: artifactapi.k8s.syd1.au.unkin.net/docker-internal/logviewer:v0.1.0
+          imagePullPolicy: IfNotPresent
+          ports:
+            - containerPort: 8080
+              name: http
+              protocol: TCP
+          env:
+            - name: CH_URL
+              value: http://clickhouse-logs.logging.svc.cluster.local:8123
+            - name: CH_USER
+              valueFrom:
+                secretKeyRef:
+                  name: clickhouse-logreader
+                  key: username
+            - name: CH_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: clickhouse-logreader
+                  key: password
+          livenessProbe:
+            httpGet:
+              path: /healthz
+              port: http
+            initialDelaySeconds: 10
+            periodSeconds: 30
+            timeoutSeconds: 5
+            failureThreshold: 3
+          readinessProbe:
+            httpGet:
+              path: /healthz
+              port: http
+            initialDelaySeconds: 5
+            periodSeconds: 10
+            timeoutSeconds: 5
+            failureThreshold: 3
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            capabilities:
+              drop:
+                - ALL
+          resources:
+            requests:
+              cpu: 100m
+              memory: 128Mi
+            limits:
+              cpu: 500m
+              memory: 512Mi
+      restartPolicy: Always

apps/base/logging/logviewer/gateway.yaml

@@ -0,0 +1,38 @@
+---
+# Internal front for the logviewer UI (cf. mediamover/pdbmux).
+apiVersion: gateway.networking.k8s.io/v1
+kind: Gateway
+metadata:
+  labels:
+    traefik.io/instance: internal
+  annotations:
+    cert-manager.io/cluster-issuer: vault-issuer
+    cert-manager.io/common-name: logviewer.unkin.net
+    cert-manager.io/private-key-size: "4096"
+    external-dns.alpha.kubernetes.io/hostname: logviewer.unkin.net
+    external-dns.alpha.kubernetes.io/target: 198.18.200.4
+  name: logviewer
+  namespace: logging
+spec:
+  gatewayClassName: traefik-internal
+  listeners:
+    - allowedRoutes:
+        namespaces:
+          from: Same
+      hostname: logviewer.unkin.net
+      name: http
+      port: 80
+      protocol: HTTP
+    - allowedRoutes:
+        namespaces:
+          from: Same
+      hostname: logviewer.unkin.net
+      name: https
+      port: 443
+      protocol: HTTPS
+      tls:
+        certificateRefs:
+          - group: ""
+            kind: Secret
+            name: logviewer-tls
+        mode: Terminate

apps/base/logging/logviewer/httproute.yaml

@@ -0,0 +1,49 @@
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: logviewer-http-redirect
+  namespace: logging
+spec:
+  hostnames:
+    - logviewer.unkin.net
+  parentRefs:
+    - group: gateway.networking.k8s.io
+      kind: Gateway
+      name: logviewer
+      sectionName: http
+  rules:
+    - filters:
+        - type: RequestRedirect
+          requestRedirect:
+            scheme: https
+            statusCode: 301
+      matches:
+        - path:
+            type: PathPrefix
+            value: /
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: logviewer
+  namespace: logging
+spec:
+  hostnames:
+    - logviewer.unkin.net
+  parentRefs:
+    - group: gateway.networking.k8s.io
+      kind: Gateway
+      name: logviewer
+      sectionName: https
+  rules:
+    - backendRefs:
+        - group: ""
+          kind: Service
+          name: logviewer-oauth2
+          port: 80
+          weight: 1
+      matches:
+        - path:
+            type: PathPrefix
+            value: /

apps/base/logging/logviewer/kustomization.yaml

@@ -0,0 +1,12 @@
+---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - vaultstaticsecret.yaml
+  - deployment.yaml
+  - oauth2-proxy-configmap.yaml
+  - oauth2-proxy-deployment.yaml
+  - service.yaml
+  - gateway.yaml
+  - httproute.yaml

apps/base/logging/logviewer/oauth2-proxy-configmap.yaml

@@ -0,0 +1,32 @@
+---
+# Non-secret oauth2-proxy configuration (client_id/secret/cookie_secret come
+# from the logviewer-oauth-credentials Secret). Single auth front for the
+# logviewer UI: everything requires an Authentik session in akP-logviewer-admin.
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: logviewer-oauth2-env
+  namespace: logging
+data:
+  OAUTH2_PROXY_HTTP_ADDRESS: "0.0.0.0:4180"
+  OAUTH2_PROXY_PROVIDER: "oidc"
+  # Authentik logviewer app discovery issuer (terraform-authentik PR #21).
+  OAUTH2_PROXY_OIDC_ISSUER_URL: "https://identity.unkin.net/application/o/logviewer/"
+  OAUTH2_PROXY_REDIRECT_URL: "https://logviewer.unkin.net/oauth2/callback"
+  OAUTH2_PROXY_UPSTREAMS: "http://logviewer.logging.svc.cluster.local:8080/"
+  OAUTH2_PROXY_SCOPE: "openid email profile ak_groups"
+  # Populate session.Groups from the Authentik ak_groups claim.
+  OAUTH2_PROXY_OIDC_GROUPS_CLAIM: "ak_groups"
+  OAUTH2_PROXY_ALLOWED_GROUPS: "akP-logviewer-admin"
+  OAUTH2_PROXY_PASS_USER_HEADERS: "true"
+  OAUTH2_PROXY_EMAIL_DOMAINS: "*"
+  # Authentik hardcodes email_verified=false in the id_token; authorization is
+  # enforced via ak_groups, so accepting the unverified email is safe.
+  OAUTH2_PROXY_INSECURE_OIDC_ALLOW_UNVERIFIED_EMAIL: "true"
+  OAUTH2_PROXY_COOKIE_SECURE: "true"
+  OAUTH2_PROXY_COOKIE_DOMAINS: "logviewer.unkin.net"
+  OAUTH2_PROXY_WHITELIST_DOMAINS: "logviewer.unkin.net"
+  OAUTH2_PROXY_REVERSE_PROXY: "true"
+  OAUTH2_PROXY_PROVIDER_CA_FILES: "/etc/ssl/combined/ca-certificates.crt"
+  OAUTH2_PROXY_CODE_CHALLENGE_METHOD: "S256"
+  OAUTH2_PROXY_SKIP_PROVIDER_BUTTON: "true"

apps/base/logging/logviewer/oauth2-proxy-deployment.yaml

@@ -0,0 +1,132 @@
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: logviewer-oauth2
+  namespace: logging
+  annotations:
+    configmap.reloader.stakater.com/auto: "true"
+    secret.reloader.stakater.com/reload: "logviewer-oauth-credentials,vault-ca-cert"
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: logviewer-oauth2
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+    type: RollingUpdate
+  template:
+    metadata:
+      labels:
+        app: logviewer-oauth2
+    spec:
+      serviceAccountName: default
+      automountServiceAccountToken: false
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 65532
+        runAsGroup: 65532
+        fsGroup: 65532
+        seccompProfile:
+          type: RuntimeDefault
+      initContainers:
+        # identity.unkin.net serves a Vault-PKI cert; combine the system roots
+        # with the internal CA so oauth2-proxy's OIDC HTTP client trusts it.
+        - name: combine-certs
+          image: artifactapi.k8s.syd1.au.unkin.net/dockerhub/library/alpine:3
+          imagePullPolicy: IfNotPresent
+          command:
+            - sh
+            - -c
+            - cat /etc/ssl/certs/ca-certificates.crt /custom-ca/ca.crt > /combined-certs/ca-certificates.crt
+          volumeMounts:
+            - name: vault-ca-cert
+              mountPath: /custom-ca
+              readOnly: true
+            - name: combined-certs
+              mountPath: /combined-certs
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            capabilities:
+              drop:
+                - ALL
+          resources:
+            requests:
+              cpu: 50m
+              memory: 32Mi
+            limits:
+              cpu: 200m
+              memory: 64Mi
+      containers:
+        - name: oauth2-proxy
+          image: quay.io/oauth2-proxy/oauth2-proxy:v7.15.3
+          imagePullPolicy: IfNotPresent
+          ports:
+            - containerPort: 4180
+              name: http
+              protocol: TCP
+          envFrom:
+            - configMapRef:
+                name: logviewer-oauth2-env
+                optional: false
+          env:
+            - name: OAUTH2_PROXY_CLIENT_ID
+              valueFrom:
+                secretKeyRef:
+                  name: logviewer-oauth-credentials
+                  key: client_id
+            - name: OAUTH2_PROXY_CLIENT_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: logviewer-oauth-credentials
+                  key: client_secret
+            - name: OAUTH2_PROXY_COOKIE_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: logviewer-oauth-credentials
+                  key: cookie_secret
+          volumeMounts:
+            - name: combined-certs
+              mountPath: /etc/ssl/combined
+              readOnly: true
+          livenessProbe:
+            httpGet:
+              path: /ping
+              port: http
+            initialDelaySeconds: 10
+            periodSeconds: 30
+            timeoutSeconds: 5
+            failureThreshold: 3
+          readinessProbe:
+            httpGet:
+              path: /ready
+              port: http
+            initialDelaySeconds: 5
+            periodSeconds: 10
+            timeoutSeconds: 5
+            failureThreshold: 3
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            capabilities:
+              drop:
+                - ALL
+          resources:
+            requests:
+              cpu: 50m
+              memory: 64Mi
+            limits:
+              cpu: 500m
+              memory: 256Mi
+      volumes:
+        - name: vault-ca-cert
+          secret:
+            secretName: vault-ca-cert
+            items:
+              - key: ca.crt
+                path: ca.crt
+        - name: combined-certs
+          emptyDir: {}
+      restartPolicy: Always

apps/base/logging/logviewer/service.yaml

@@ -0,0 +1,36 @@
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: logviewer
+  namespace: logging
+spec:
+  internalTrafficPolicy: Cluster
+  ports:
+    - name: http
+      port: 8080
+      protocol: TCP
+      targetPort: http
+  selector:
+    app: logviewer
+  sessionAffinity: None
+  type: ClusterIP
+---
+# Front-door entry Service: the HTTPRoute for logviewer.unkin.net targets this;
+# all traffic enters via oauth2-proxy.
+apiVersion: v1
+kind: Service
+metadata:
+  name: logviewer-oauth2
+  namespace: logging
+spec:
+  internalTrafficPolicy: Cluster
+  ports:
+    - name: http
+      port: 80
+      protocol: TCP
+      targetPort: http
+  selector:
+    app: logviewer-oauth2
+  sessionAffinity: None
+  type: ClusterIP

apps/base/logging/logviewer/vaultstaticsecret.yaml

@@ -0,0 +1,21 @@
+---
+# Authentik OIDC client for logviewer (client_id, client_secret, cookie_secret)
+# seeded at kv/kubernetes/namespace/logging/default/oauth-credentials; the
+# logging/default templated policy already grants read, so no terraform-vault
+# change is needed.
+apiVersion: secrets.hashicorp.com/v1beta1
+kind: VaultStaticSecret
+metadata:
+  name: logviewer-oauth-credentials
+  namespace: logging
+spec:
+  destination:
+    create: true
+    name: logviewer-oauth-credentials
+    overwrite: true
+  hmacSecretData: true
+  mount: kv
+  path: kubernetes/namespace/logging/default/oauth-credentials
+  refreshAfter: 5m
+  type: kv-v2
+  vaultAuthRef: default